Microstructure and mechanical properties of Ni-based diamond composite coatings vacuum brazed on high-nitrogen steel surface using a novel Ni_38.69Ti_18.93Cr_6.85Zr_12.07V_6.71Cu_16.75 filler

Ni-based diamond composite coatings exhibit high thermal conductivity, superior wear resistance, and robust corrosion resistance. These advantages effectively extend the service life of high‑nitrogen steel (HNS). This study introduces a novel Ni-based filler designed using cluster theory to fabricate Ni-based diamond composite coatings. The cluster-plus-glue-atom model [Ti-Ti4Ni7]Ni was established to design the composition of this filler. Subsequently, its composition Ni_38.69Ti_18.93Cr_6.85Zr_12.07V_6.71Cu_16.75(wt%) was confirmed based on the principle of substituting similar elements. After ball milling with diamond particles, the composite coating was successfully vacuum brazed onto the HNS surface. This paper examines the intrinsic relationship between the microstructure, mechanical properties, and electrochemical performance of the composite coating. The findings reveal a strong metallurgical bond between the coating and HNS. At a brazing temperature of 1080 °C, the Ni-based diamond composite coating exhibited minimal cracking and porosity, with diamond particles optimally exposed. The coating demonstrated superior stability and exceptional wear resistance, which can be attributed to the high-hardness Cr₂Ti phase formed at the HNS/Ni-based filler interface. Additionally, at 1080 °C, the coating showed high open-circuit potential in a 3.5 wt% sodium chloride solution, indicating excellent corrosion resistance.